Device for adjusting the idling in an internal combustion engine

ABSTRACT

The regulation of the idle speed of an internal combustion engine under no-load conditions is effected by a compensating chamber which communicates with the intake ducts of the several cylinders of the engine. Manual adjustment means (such as a screw) is used to adjust the flow passage area in the small ducts until a satisfactory adjustment is achieved.

United States Patent Garcea [54] DEVICE FOR ADJUSTING THE IDLING IN ANINTERNAL COMBUSTION ENGINE Inventor: Giampaolo Garcea, Milan, ItalyAssignee: Alia Romero S.p.A., Milan, Italy Filed: July 8, 1970 Appl.No.: 53,217

Foreign Application Priority Data July 15, 1969 Italy ..19,672 N69 US.Cl. ..l23/l24 R, 123/52 M, 123/127, 123/199 D, 123/139 AW, 123/119 DBInt. Cl ..F02m 23/04, FOZm 13/04 Field ofSearch ..123/119 D, 119 DB,124, 127, 123/52 B, 52 M, 139 AW 51 May 23,1972

Primary Examiner-Wendell E. Burns Attorney-Holman & Stern ABSIRACT Theregulation of the idle speed of an internal combustion engine underno-load conditions is effected by a compensating chamber whichcommunicates with the intake ducts of the several cylinders of theengine. Manual adjustment means (such as a screw) is used to adjust theflow passage area in the small ducts until a satisfactory adjustment isachieved 5 Clains, 4 Drawing Figures the engine idle operation isexperienced. The remaining and less considerable fraction of thepressure drop aforesaid is experienced in correspondence with theadjustable restricted port. It is only this latter remaining fraction ofthe pressure drop which draws into the cavity through the other smallducts, the mixture (or air) contained in the sections of the ducts ofthe other cylinders which is provided between the closed throttles andthe intake valves which, for the other cylinders, are temporarilyclosed. From these duct sections, which can be considered as closedspaces having a constant volume, the fluid emerges as drawn by theaforementioned fraction of the overall pressure drop and flows into thecommon cavity only until such time as the pressure in the duct sectionequals the pressure in the cavity.

If the volume of fluid which thus leaves the section of the intake ductof the other cylinders is less than the internal volume of the smallduct, and if the latter is so shaped that the fluid emerging from theduct sections of the other cylinders pushed before it the fluid whichwas present in the small duct without being admixed therewith, one canrealize, as has been obtained, that only the fluid contained in thesmall duct enters the common capacity, It is thus avoided that the fluidwhich was contained in the closed portion of the intake duct, a fluidwhich was polluted by the reflown gases during the preceding cycles ofthe other cylinders, may enter the common capacity thus giving rise toirregular operation. In the capacity, only that fluid enters, which wascontained in the small duct, a fluid which is formed by a non pollutedmixture (or air) entered at the end of the preceding induction stroke ofthe corresponding cyclinder.

Another feature of the present device consists in that the degree ofclosure of the throttles of the several cylinders is such that the rateof flow of the mixture (or air) which flows through the passageway asconfined by the peripheral edge of the closed throttle and by theinternal cylindrical wall of the duct is a fraction, of less thanpercent, of the overall feed rate of flow of the cylinder. The remainingfraction of the rate of flow obviously flows through the restrictedports having a fixed and variable calibration which are arrangedserially with respect to one another and in parallel with respect to thethrottle. With a rate of flow in correspondence with the throttle, thuslimited as above set forth, possible, even'discrete, variations due tomisalignments of the throttles or deposits on the throttles, (which aresomewhat different according to the throttle) a difference in feeding tothe several cylinders which is quite acceptable is experienced.

A further improvement over what has been described above can beintroduced for the operation of the device, by replacing the restrictedport with a fixed calibration in each of the in dividual ducts, by twoor more serially arranged restricted ports. In the light of what hasbeen described, during the induction stroke of a cylinder with an idlingengine, the pressure ratio upstream-downstream of the restricted portcan not only be higher than the critical ratio but even higher than thesquare power of the critical ratio. A single restricted port should thusbe oversized (to obtain the rate of flow which is necessary to ensurefeeding) since the speed would never exceed sonic speed. Such anoversizing is detrimental when, during the induction strokes of theother cylinders, the flow which may cause the pollution of the capacityflows in the reverse direction (with pressure ratios which are alwaysconsiderably below the critical ratio). With two or three restrictedports in series, the ratio of the direct feeding flow to the reversedflow (susceptible of originating pollution) is thus more favorable.

The above and other objects and advantages of the invention will becomemore readily apparent to persons skilled in the art from the followingdetailed description and annexed drawings, and in which drawings:

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a top plan view, partly incross-section of a four cylinder engine having the cylinders in line,

FIG. 2 is a fragmentary front view, partly in cross-section of theengine shown in FIG. 1,

FIG. 3 is a fragmentary cross-sectional view showing the restrictedfixed port at the opening of the small intake duct of a cylinder, and

FIG. 4 is a fragmentary cross-sectional view showing the fixedcalibration being obtained with two serially arranged restricted ports.

DETAILED DESCRIPTION OF THE DRAWINGS Referring to FIG. 1, there isillustrated an internal combustion engine E provided with a block Bhaving four cylinders l, 2, 3 and 4 arranged in line. The engine isprovided with valve seats 5 and 6 for intake and exhaust valves 16 and19 respectively. The valve seat 5 is in communication with a main intakeduct 7 in which is mounted a throttle 8, with the throttle beingillustrated in the closed position. The valves 16 and 19 are operated bycams 14a and 17a on intake cam shaft 14 and exhaust cam shaft 17respectively, with the cams coacting with heads 15 and 18 respectively.In FIG. 2, the intake valve 16 is illustrated in the open position andthe exhaust 19 in the closed position. A piston 20 provided with aconnecting rod 21 is shown in an intermediate position of the inductionstroke and the cylinder 1 in its induction phase.

Of course, it is to be understood that each of the cylinders 2, 3 and 4is provided with the above-discussed components.

A distributing chamber or space 1] is located downstream of a restrictedport 12 and the calibration of such port is adjustable by means of ascrew 13 having a conical tip 13a. By the proper manipulation of thescrew 13, the conical tip 13a can be caused to penetrate to a greater orlesser extent in the port 12 for adjusting the flow rate of the fluid tothe chamber 1 1.

It will be noted that a plurality of small ducts 10, preferably ofresilient material, extend from the chamber 11 to the main intake duct 7in parallelism with respect to the throttle 8. It will be understoodthat there is one duct 10 for each cylinder of the engine. Each duct 10is in communication with the interior of each main duct 7 via arestricted port 9. As shown in FIG. 3, the restricted port 9 is providedin a sleeve 9a threaded into an opening provided in the main duct 7. Theend of the small duct 10 is affixed to the sleeve 9a by a suitableclamping means or the like 9b.

In FIG. 4, it will be noted that the fixed calibration is obtained bytwo serially arranged respective ports. More specifically, in thisembodiment a sleeve is also threaded into a bore in the main duct 7 withthe inner end of the sleeve having a restricted port 9d and the outerend of the sleeve a restricted port 92. The small duct 10 is attached tothe sleeve by suitable clamping means 9 f The air drawn by the inductionstroke of the piston 20 reaches the intake duct 7 of the cylinder 1through the restricted port 9 having a fixed calibration, incorrespondence with which it undergoes a considerable pressure drop.Through the small duct 10, the air is drawn into the chamber 1 1 and dueto the effect of the negative pressure not only the mixture or the airis drawn through the port 12 having a variable calibration, but also themixture or the air contained in the small ducts relative to thecylinders 2, 3 and 4. By proportioning the ports, in this phase throughthe small ducts of the cylinders 2, 3 and 4, the cavity is reached onlyby the mixture or the air which was contained in said ducts, rather thanthe fluid which was contained in the intake ducts 7 of the cylinders 2,3 and 4. By so doing, the mixture (or the air) cannot reach the cavitywhich, in the intake ducts 7 of the cylinders 2, 3 and 4 was polluted bythe preceding reflow of exhaust gases of the corresponding cylinders.

What is claimed is:

1. In an internal combustion engine having a plurality of cylinders, apiston in each cylinder, an intake opening for each cylinder, a mainintake duct leading to each intake opening and a throttle valve in eachmain intake duct, a control device for the idle running of the engineduring no-load conditions,

DEVICE FOR ADJUSTING THE IDLING IN AN INTERNAL COMBUSTION ENGINEBACKGROUND OF THE INVENTION This invention relates to a control devicefor adjusting the idling of an internal combustion engine during no-loadconditions.

It is known that very often, in order to increase the specific power ofan alternative internal combustion engine, dynamic phenomena connectedwith the pulsatory trend both of the mixture (or air)in the intakeducts, and of the gases in the exhaust ducts are resorted to. The lengthand the cross-sectional area of the ducts in to neighborhood of thevalves of the individual cylinders of the engine are optimized to thispurpose. It is also known that the best exploitation of such phenomenais obtained by a phase adjustment in the distribution assembly so that,in the vicinity of the end of stroke, that is, between the end of theexhaust stroke and the beginning of the induction stroke, the intake andexhaust valves are kept somewhat open simultaneously, in the sense thatthe intake valve has already begun to open and the exhaust valve is notyet completely closed. The phase adjustments which optimize the enginepower under fiat-out conditions, however, give rise to irregular feedphenomena when the engine is throttled whenever throttling is obtainedwith a single throttle for two or more cylinders. These irregularitiesare especially experienced at full throttling, that is when the engineruns idly at its minimum R.P.M. and also on stoppage since the engineoften continues to run even when the current feed to the spark plug hasbeen discontinued. It is known that, in order to do away with theseirregularities in engines having a high specific power, the intake ductsof the individual cylinders are each equipped with a correspondingthrottle. Thus, there are as many throttles as there are cylinders inthe engine. It is also known that usually in the internal combustionengine, when the throttle is closed, that is when throttling is at amaximum (that which corresponds in motor cars to the accelerator pedalbeing wholly released), the engine is fed with a mixture (or air in theinjection engines) essentially through a small duct arranged in parallelwith respect to the section of the main duct in which the throttle islocated, so that this small duct shortcircuits the throttle when thelatter is closed. In the interior of the small duct, a restricted port,whose cross-sectional area can be manually varied by the motorist,permits an adjustment of the rate of flow of the feeding mixture (orair) so as to obtain the desired rate of rotation of the engine whenidling under no-load conditions. It is known that this adjustment isnecessary, since even small differences, both initially and during theservice life of the motor car, in the mechanical and thermal efficiencyof mass-produced engines, can originate values of the idling R.P.M.which are sharply different from the desired values. Also, in the aboveoutlined case of engines having as many throttles as there arecylinders, the engine feed with the closed throttles takes placeessentially through the small ducts which are arranged in parallel withrespect to the throttles. In the interior of the small ducts there isthe manually adjustable restricted port above mentioned.

With such an arrangement, the adjustment operation can be carried outwith difficulty since the desired R.P.M. rating can be obtained withrates of flow of a mixture (or air) which are radically different fromone cylinder to another. Only if the motorist has suitable control meansavailable, can these differences be reduced within an acceptable range.Such control means, however, to be satisfactory, must be ratherintricate and expensive, so that the motorist cannot resort to suchcontrol means for adjustments during the service life of the car engine.

In spite of these difficulties, however, the above arrangement (as manymanually adjustable ports as there are throttles) is generally adoptedsince, if the intake ducts of the several cylinders are fed, underclosed throttle conditions, with small ducts place in parallel and fedby a single adjustable restricted port, all the irregularity phenomenadesired to be overcome by adopting as many throttles as there arecylinders in the engine, are experienced again.

Theoretical investigations and experimental runs have been carried outby the applicant in recent years on the physical reasons for theirregularity phenomena above mentioned and thus also on the possibilityof overcoming the phenomena. Already a few years ago one of theprincipal reasons for the irregular run and the difficult stoppage ofthe engine as above stated has been identified. A substantial deepmodification of the chemical structure of the gasoline hydrocarbonstakes place when, in the intake ducts, there is an excessive reflow ofexhaust gases due to the simultaneous opening of the intake and exhaustvalves during a partial throttling operation. This phenomenon, due tooverheating of the hydrocarbons of the fresh mixture admixed with theexhaust gases, naturally takes a certain time to occur and is thus themore pronounced, the longer is the time available, that is at lowrotation speeds and when idling. The same is true the greater is theamount of reflow gases. Having a throttle available for each cylinder,the volume which is internal to the duct section provided between thethrottle and the intake valves is much smaller and the same is true ofthe reflow of exhaust gases which is sufficient to cancel the pressuredifferential which originates the reflow phenomenon as itself.

Another important reason for the irregular operation has beenidentified. However, if the reflow of the exhaust gases from a cylinderenters the induction manifold which is common to a plurality ofcylinders, inasmuch as the short time available does not permit aperfect admixture of the exhaust gases with the feeding mixture (or theair) contained in the manifold, a fraction of the reflow gases can beimmediately drawn into the cylinder, but other fractions are drawn bythe other cylinders. The splitting of the several fractional reflowstreams, of course, is wholly at random and is unpredictable so that thedegree of pollution of the draw-in mixture (or air) is different fromone cylinder to another cylinder but is also different, for the samecylinder, from one cycle to another. The result, obviously, is anirregular operation of the engine, and this irregularity is still moreserious in the case of an injection engine since the amount of injectedfuel is always the same for all of the cylinders and along the severalsequential cycles of a certain cylinder, whereas this does not occur forthe drawn-in air. These results of the theoretical and experimentaltrials on the reasons for the irregularity phenomena have permitted theidentification of the possibility of preventing such irregular operationby means of a device for the manual adjustment of the idle running ofengines having as many throttles as there are cylinders.

SUMMARY OF THE INVENTION More particularly, such device affordsconsiderable advantages as to the simplicity of construction andespecially as to the convenience in the manual adjustment operationaforementioned. The adjustment is carried out, in fact, in the presentdevice, by acting on a single restricted port whose flow passage sectionis adjustable and through which the mixture (or air) stream is caused toflow for feeding several cylinders or also all of the cylinders of theengine when the throttles are closed. Obviously, downstream of therestricted port there is a cavity from which extend small ducts equal innumber to the cylinders fed by the device, and the small ducts open intothe intake ducts of the several cylinders. By so doing, through thesmall ducts and the cavity, the several cylinders are also incommunication with each other so that the reflow of exhaust gases from acylinder could irregularly and unpredictably pollute the other cylindersunless the device does not embody as an integral part thereof, furtherrestricted ports having a fixed calibration and arranged in theindividual small duets, with the ports being so proportioned that,during the induction stroke of a cylinder in correspondence with therespective fixed restricted port, a considerable fraction of thepressure drop (with respect to atmospheric pressure) which is requiredfor said control device including a distributing chamber, a small ductfor each cylinder, each small duct being in communication at one endwith the distributing chamber, and the opposite end of each of saidsmall ducts being in communication, through at least one restricted porthaving a fixed calibration, with a main intake duct downstream of thethrottle an inlet opening upstream of the distributing chamber throughwhich a fluid to be fed to the cylinders enters the distributingchamber, and a screw having a conical tip cooperable with the inletopening for adjusting the flow rate of the fluid to the cylinders.

2. The device according to claim 1 characterized in that the length ofeach of the small ducts is at least times the inside diameter of theduct.

3. The device according to claim 1, characterized in that, when thethrottle is closed, the remaining flow passageway in correspondence withthe edges of the throttle has an area which is by 25 percent smallerthan the flow passageway of the cross-section of the fixed restrictedport.

4. The device according to claim 1, characterized in that said smallducts are in communication with the respective intake ducts through aplurality of restricted ports having a fixed calibration and seriallyarranged with respect to each other.

5. The device according to claim 1, characterized in that the restrictedports having a fixed calibration are mounted in correspondence of thepoints at which the small duct open into the intake ducts, or incorrespondence with the points at which the small ducts open into thecapacity, or in an intermediate portion of said small ducts.

UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No.3,664,316 Dated 23 May 1972 Invnt6r(S) iampaolo GARCEA It is certifiedthat error appears in the above-identified patent and that said LettersPatent are hereby corrected as shown below:

On the Abstract page, Item [73] Assignee the Assignee's name is spelledwrong and should be ALFA ROMEO S. p. A.

Signed and sealed this 31st day of October- 1972.

(SEAL) Attest:

EDWARD M.FLETCHER,JR. ROBERT GOTTSCHALK Commissioner of PatentsAttesting Officer USCOMM-DC 60376-P69 fi us. GOVERNMENT PRINTING OFFICE:I969 o3ss-su FORM PO-lOSO (10-69)

1. In an internal combustion engine having a plurality of cylinders, apiston in each cylinder, an intake opening for each cylinder, a mainintake duct leading to each intake opening and a throttle valve in eachmain intake duct, a control device for the idle running of the engineduring no-load conditions, said control device including a distributingchamber, a small duct for each cylinder, each small duct being incommunication at one end with the distributing chamber, and the oppositeend of each of said small ducts being in communication, through at leastone restricted port having a fixed calibration, with a main intake ductdownstream of the throttle an inlet opening upstream of the distributingchamber through which a fluid to be fed to the cylinders enters thedistributing chamber, and a screw having a conical tip cooperable withthe inlet opening for adjusting the flow rate of the fluid to thecylinders.
 2. The device according to claim 1, characterized in that thelength of each of the small ducts is at least 10 times the insidediameter of the duct.
 3. The device according to claim 1, characterizedin that, when the throttle is closed, the remaining flow passageway incorrespondence with the edges of the throttle has an area which is by 25percent smaller than the flow passageway of the cross-section of thefixed restricted port.
 4. The device according to claim 1, characterizedin that said small ducts are in communication with the respective intakeducts through a plurality of restricted ports having a fixed calibrationand serially arranged with respect to each other.
 5. The deviceaccording to claim 1, characterized in that the restricted ports havinga fixed calibration are mounted in correspondence of the points at whichthe small duct open into the intake ducts, or in correspondence with thepoints at which the small ducts open into the capacity, or in anintermediate portion of said small ducts.